Foreword -- Introduction -- Part I: Gifts from ancient volcanoes -- What are geodes? -- The mysterious formation of geodes in igneous rocks -- Incredible coconuts: Mexican coconut geodes -- When geodes are gems -- More Latin surprises -- Geode curiosities -- Part II: Gifts from prehistoric seas -- From sediments to glamour -- Wonderful Warsaw -- Strange geodes of Indiana -- A few bonuses -- Amethyst surprises and baby rattle rocks -- Florida's ocean harvest -- Not always quartz -- Strange, stranger, strangest -- Part III: Thundereggs and more -- Dozens of eggs: United States; Mexico; Canada; Opening thundereggs -- Almost geodes: concretions and septarians -- Summary -- Geologic time scale -- Frequently asked questions about geodes -- Glossary.